rich...@karlquist.com said:
Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
20 GHz.
Thanks. That's what I was looking for.
Wiki says that SMA works to 18 GHz and the 3.5 mm is good for
Do you have a scope? Any overshoot/bounce crap? (Not likely with low
power
CMOS.)
Attached is screenshot from USB-based scope. I'll going to switch wires
to see any difference.
--
WBW,
V.P.attachment: gps2rtc.PNG___
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On 2/26/14 12:44 AM, Hal Murray wrote:
rich...@karlquist.com said:
Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
20 GHz.
Thanks. That's what I was looking for.
Wiki says that SMA
To answering myself: I think nothing wrong with DS32XX. I hooked up GPS
1PPS output to the same timer (different channel) where I have 1PPS from
RTC. Now I see something like this.
# Delta GPS: 7330, Delta RTC: 7330
# Delta GPS: 7330, Delta RTC: 7329
# Delta GPS: 7330, Delta RTC: 7329
#
I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt
is attached.
I'd like to be able to share the serial port between LH and NTP so that I can
run the machine as an NTP Stratum 1 server locked to the TB, and also be able
to use LH to check things.
I looked around the
I've been experimenting with digital thermal compensation on my GPSDO. The
results have been favorable for a 14 bit dithered PWM-based DAC, but leaves a
bit to be desired in the big picture. And it takes up a lot of program bytes
on my PIC.. What's the general consensus on this? Should
Gravity Probe A used Hydrogen Masers to verify gravitational rate change.
1976 and suborbital, so not exactly the same as Red Shift mentioned in
the HP note.
I myself participated in a variation of Pound-Rebka-Snider (Mossbauer
nuclear physics techniques) in the 1980's.
On Mon, Feb 24, 2014 at
On Wed, 26 Feb 2014 08:09:44 -0800 (PST)
Bob Stewart b...@evoria.net wrote:
I've been experimenting with digital thermal compensation on my GPSDO.
The results have been favorable for a 14 bit dithered PWM-based DAC, but
leaves a bit to be desired in the big picture. And it takes up a lot of
I'm running Meinberg NTP on the Windows 7 x64 machine to which my
Thunderbolt is attached.
I'd like to be able to share the serial port between LH and NTP so that I
can run the machine as an NTP Stratum 1 server locked to the TB, and also be
able to use LH to check things.
I looked around
Hi Atilla,
The GPSDO is VE2ZAZ's circuit with new code. It detects phase crossings to
change the DAC, so it has a phase crossing for every update. I'm working on a
TIC design but haven't started on the hardware. In the interim, I hooked up an
LM34 thermistor and have been playing with that.
It's not going to work.
If the purpose of running the Thunderbolt is only to drive NTP then
you don't need LH. NTP's only tags the pulses to the nearest
microsecond, nano sec on accuracy is lost on NTP. I'd even say the
TB is the wrong GPS for NTP. It costs to much and uses to much power.
Here is interesting topic about NTP on Raspberry PI (typical usage of
ARM and Linux bread on top of it)
http://www.synclab.org/?tag=testing
Basically, TCP stack on ARM usually come from one source - its a Adam
Dunken TCP stack. Then its is MII part and the hardware which doing
Ethernet.
I have some problems with My 8505A
Analyzer, it has no RF output, I checked the YTO and other frequency dividers
and it appears to be OK some times there is RF output only it will not tune and
it seems to cut out as I tune trough the frequency range.
Thank You
Sal C. Cornacchia Electronic RF
Ummm think you sent the question to the wrong group perhaps?
On Wed, Feb 26, 2014 at 12:50 PM, corc...@yahoo.ca wrote:
I have some problems with My 8505A
Analyzer, it has no RF output, I checked the YTO and other frequency
dividers
and it appears to be OK some times there is RF output only
Hi Bob,
better use an FIR.
Your rolling average didn't smooth out enough because it doesn't have
a cutoff low enough.
Hysteresis is not going to help here that I know of.
Cheers,
D.
On Wed, Feb 26, 2014 at 6:05 PM, Bob Stewart b...@evoria.net wrote:
Hi Atilla,
The GPSDO is VE2ZAZ's circuit
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If you can understand the temperature effects and can model them
accurately and you can measure temperatures and your DAC steps are
small enough, then digital compensation can be perfect. But you
are unlikely to meet all those conditions. In theory if the problem
is that the voltage diver's
david.partri...@perdrix.co.uk said:
I looked around the with Google, and saw *numerous serial port splitters.
Which is recommended?
If your lines are short, you don't need fancy hardware. The RS-232 driver
will drive 2 lines. Just take 2 cables, cut them in half, connect the
wires...
On Wed, Feb 26, 2014 at 12:32 PM, Chris Albertson albertson.ch...@gmail.com
wrote:
You can NOT control a GPS from two ports. Both NTP and LH will try to
send commands to the GPS.
Actually the Palisades driver doesn't send commands to the Thunderbolt. It
sends a single invalid command
On Wed, Feb 26, 2014 at 9:53 AM, d0ct0r t...@patoka.org wrote:
Here is interesting topic about NTP on Raspberry PI (typical usage of ARM
and Linux bread on top of it)
The article addresses using the Pi as an NTP server with stratum 0.
In other words as an NTP server that uses another NTP
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From: Chris Albertson
[]
Except as an exercise there is almost no point any more using GPS to
drive a local NTP server if you have a very good Internet connection.
My fiber Internet connection is as good as Ethernet as the Pool
Servers work well for me. Those using slower or a widely shared
On Wed, Feb 26, 2014 at 11:15 AM, David J Taylor
david-tay...@blueyonder.co.uk wrote:
The Raspberry Pi with GPS/PPS certainly beats any internet connection I've
ever had delivered to this house, though:
Yes it will. But the point of the server is to deliver time to other
computers. The the
From: Chris Albertson
Sent: Wednesday, February 26, 2014 7:32 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Serial port splitter s/w
On Wed, Feb 26, 2014 at 11:15 AM, David J Taylor
david-tay...@blueyonder.co.uk wrote:
The Raspberry Pi with GPS/PPS
Chris, even with Wi-Fi connected computers, mostly running Windows, there
is a huge difference between talking to a stratum-1 server on my LAN
compared to running just Internet servers. Our experiences differ, as I am
on a cable modem connection from the UK's Virgin Media. Folks need to
On Wed, Feb 26, 2014 at 2:05 PM, Chris Albertson
albertson.ch...@gmail.comwrote:
Chris, even with Wi-Fi connected computers, mostly running Windows, there
is a huge difference between talking to a stratum-1 server on my LAN
compared to running just Internet servers. Our experiences differ,
Fluke used two different connector schemes for the DC input on 732A
battery packs. The oldest units have a pair of banana jacks, and
later units use a 3-pin connector made by Hypertronics. My question
concerns only the latter (732A battery packs with the Hypertronics connectors).
The
You guys have me persuaded - I'll get a Raspberry Pi ...
Regards,
David Partridge
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of David J Taylor
Sent: 26 February 2014 19:15
To: Discussion of precise time and frequency measurement
Serial outputs can usually drive several serial inputs if the cables are
short (to avoid reflections). You can wire it yourself, serial out from
the TB to both LH and NTP, serial in from LH only.
David
On 2/26/14 11:51 AM, David J Taylor wrote:
I'm running Meinberg NTP on the Windows 7 x64
Hi
One of the more common explanations for the 18 GHz “upper limit” is that the
broad water vapor absorption peak at about 23 GHz made systems less practical
as you went up from 18. I suspect the same water issues make certain types of
parts more difficult to fabricate.
Bob
On Feb 26, 2014,
Hi everyone,
I'm new to the list, and have been reading the recent threads on
Arduino-based GPSDOs and the pros/cons of 10-kHz vs 1-Hz time pulses with
interest.
As I understand it, there are a couple of reasons why one needs a
time-interval / phase measurement implemented outside the MCU:
1)
Hi Mark,
Not to worry. It's not really too coarse. Your method is more than enough for
millisecond or microsecond timing. Consider that everything about time
frequency is merely an exponent; avoid fuzzy words like coarse or fine. Your
approach will work just fine; many a GPSDO has been
On Wed, Feb 26, 2014 at 1:30 PM, David C. Partridge
david.partri...@perdrix.co.uk wrote:
You guys have me persuaded - I'll get a Raspberry Pi ...
You might want to think a little more about which to get. The Pi is OK and
will work fine but look at BeagleBone Black. It's a little nicer for
At this point the time measurement is quite crude, with 100-ns resolution.
But because we keep the counter running, the unknown residuals will keep
accumulating, and we should be able to average out this quantization
noise
What you are saying is With a long enough gate time you can measure
Hi Mark,
I'm neither an engineer, nor an expert, but here are my comments.
I think that the idea of 100ns/T is wrong. There are several variables that
control accuracy, but the time between pulses from your OCXO (assuming no phase
or frequency drift) isn't one of them. So, that gives 1/T.
Hello,
I know this is really a basic question.
I have a Fluke montronics frequency comparator.
It has 2 inputs, one from my GPS and one from my DUT.
After a given oscillator is warmed up, I can read the meter in parts 10 -X
There are 2 meters, One for phase 0 to 360 degrees, and one
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Hi
Not having one here, about all I can guess is that there are 360 degrees in a
cycle. If it’s going through 360 degrees in 10 seconds it’s 0.1 Hz off at what
ever point it’s comparing. If it takes 100 seconds that’s 0.01 Hz.
Yes I get this pesky decimal point stuff wrong from time to time
Hello Bob,
Thanks for the reality check.
I just wanted to make sure ,
From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wednesday, February 26, 2014 10:16 PM
Subject: Re: [time-nuts] frequency
On Feb 25, 2014, at 12:59 PM, John Seamons j...@jks.com wrote:
I may have a solution for the power-off problem that doesn't involve
batteries or supercaps. It has the added advantage of providing instant-on.
From the latest documentation:
One solution to the annoyance of having to halt the
Tom,
I took his 100ns figure to be simply the period of 10MHz. He mentioned using
an interrupt driven system, so the counts should not necessarily be limited to
100ns accuracy. At least on the PIC I'm using, the CCP and timer interrupts
don't seem to be synchronous with the PIC clock. I
That fix presumes that the power line never quits at
inappropriate times. This winter has provided me with
ample reminders that power can go out anytime.
I think a better solution would be to find a very large
super cap and power the BBB from that while giving it
a power fail interrupt to
From: Chris Albertson
You might want to think a little more about which to get. The Pi is OK and
will work fine but look at BeagleBone Black. It's a little nicer for
hardware hackers. Cost is $5 different. You can read specs and the
respective forums.
One thing to watch out for is that all
b...@evoria.net said:
At least on the PIC I'm using, the CCP and timer interrupts don't seem to be
synchronous with the PIC clock. I could be mistaken.
Unless you have a very strange architecture, it doesn't make sense for an
interrupt to not be synchronous with the CPU clock. You are in
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